Our aim of research is to investigate protein-DNA interaction in chromatin and other regulatory systems involving DNA and proteins, which are important in the control of cell differentiation, aging, cancer, genetic diseases and hormonal actions. In order to study the roles of individual amino acid residues of a protein in its interaction with DNA, we propose to study interaction between DNA and model proteins which are synthetic copolypeptides. The synthetic copolypeptides to be used will consist of one basic amino acid (lysine or arginine) and one nonbasic amino acid (alanine, serine, glycine, tyrosine for example). The presence of basic residue increases solubility of these model proteins in aqueous solvent at neutral pH so that their interaction with DNA can be studied. The roles of the nonbasic residue in each copolypeptide will be studied with respect to (1) stabilization or destabilization of native DNA structure (2) selectivity for AT or GC, (3) intercalation (aromatic residues) and (4) conformational effect on DNA. The effect on proteins themselves when they bind DNA will also be examined. The methods to be used for investigating the interaction between DNA and synthetic copolypeptide will be thermal denaturation, PMR (proton magnetic resonance), CS (circular dichroism) and other physical methods such as fluorescence, sedimentation and viscosity.